1. Field of the Invention
The present invention relates generally to an enclosure for an imaging device. The present invention is more particularly related to an enclosure for protecting an imaging device (e.g., a camera) from contamination in a machining environment, while maintaining a clear view for the imaging device to capture images.
2. Description of the Related Art
There are several applications for charge-coupled (CCD) cameras in a machine tool environment. Some examples are co-simulation, machining monitoring, and vision tool monitoring (VTM). An exemplary VTM application is illustrated in FIG. 1. A CCD camera 2 is used in a magazine automatic tool changer (ATC) 4 area to automatically detect tool breakage when a tool returns to a magazine base 8 after completing an operation. Although the area around the magazine base 8 is not subject to the harsh conditions of a machining chamber, for example in which cutting of one or more materials is performed, it does occasionally get contaminants 10 splashing from the tool/spindle or the machining chamber during tool change operations. The contaminants 10 include, for example, coolant used in the machining chamber to cool a cutting area and reduce cutting haze and/or chips resulting from the cutting. The splashing can result from the ATC motion trajectory 12, which brings the tool from the machining chamber to an imaging position 6, as illustrated in FIG. 1.
Due to the possibility of contamination, commercially available CCD cameras cannot be used directly in the magazine base 8, since most do not have the required protection (e.g., an IP54 enclosure, in which IP refers to ingress protection, the first digit “5” indicates the level of protection that the enclosure provides against solid objects, and the second digit “4” indicates the level of protection that the enclosure provides against liquids) from the contaminants 10, and none have the ability to keep the CCD camera's lens clean should coolant/chip splashing occur.
Conventionally, the CCD camera is housed in an enclosure with a low diameter aperture and air purge to solve this problem. However, high resolution images, which require a high diameter aperture, are required in a machine tool environment. Use of the air purge in the conventional manner is not feasible in the machine tool environment for the following reasons. When the machine tool is turned off at night, there is no air supply and therefore any residual coolant or mist in a high humidity environment can enter the camera enclosure and deposit as dew or condensed oil mist on the CCD camera's lens. Further, due to the required high diameter aperture, the problem of coolant and oil mist entering the camera enclosure and condensing on the CCD camera's lens is accentuated.
Accordingly, this patent application presents methods and apparatuses that effectively maintain lens cleanliness and image clarity while protecting an imaging device, such as a CCD camera, in a harsh machining environment.